Light-diffusing film having pores

ABSTRACT

Disclosed herein is a light-diffusing film having pores for use in a backlight unit of a TFT-LCD. The light-diffusing film having pores of this invention comprises a base sheet composed of a synthetic resin; a light-diffusing layer laminated on one surface of the base sheet and having pores formed by applying a composition including a light-diffusing resin and light-diffusing particles contained in the light-diffusing resin under controlled composition supply pressure of 1˜5 kgf/cm 2  and travel speed of the base sheet of 10˜200 m/min; and an antiblocking layer laminated on the other surface of the base sheet. According to this invention, the light-diffusing film has improved total light transmittance and light diffusibility owing to the pores formed in the light-diffusing layer, and is thus usefully applicable to a backlight unit of a TFT-LCD.

BACKGROUND

The present invention relates to a light-diffusing film having pores foruse in a backlight unit of a TFT-LCD (Thin Film Transistor-LiquidCrystal Display), and more particularly, to a light-diffusing film, inwhich pores are formed in a light-diffusing layer laminated on onesurface of a base sheet, thereby increasing total light transmittanceand light diffusibility.

In general, LCDs can be manufactured to be small and ultra slim, and canrealize low power consumption and high image quality, and thus arereceiving attention for use as various mobile image display devices orstationary image display devices. However, in the display using liquidcrystals, the liquid crystal itself has no emission properties, unlikeother flat displays, and an additional emission unit is thus required toincrease the brightness of a display screen.

The emission process for the additional emission unit is largelyclassified into a front-light process and a backlight process. In thefront-light process, a light source is attached over the front surfaceor front lateral surface of the display to illuminate the surface of thedisplay. However, as the size of the display is increased, it isdifficult to realize techniques for uniformly diffusing light from thelight source over the surface of the display. Further, unlike thebacklight process mentioned below, when the light is radiated from thefront lateral side, reflective light is generated from the surface ofthe display, and limitations are imposed on designing the front surfaceof the display.

Meanwhile, the backlight process is an indirect lighting process forenhancing the brightness of a display screen in a manner such that lightoriginating from the light source of a backlight unit mounted to theback surface of a display device is transferred to the opposite sidethrough a light guide plate and then reflected at a reflective plate,such as a metal deposition plate or an opaque white plate, to allow thelight to move forward. Thus, the backlight process is a light emissiontechnique capable of overcoming the problems of the above-mentionedfront-light process. In the backlight process, although methods ofdisposing large numbers of light sources to a backlight unit or ofincreasing the power of the light source itself have been devised inorder to provide clear and bright images, they suffer because the heatgeneration and power consumption rates of the backlight unit areincreased, undesirably reducing the lifetime of products. In particular,in the case of mobile image display devices, operation time may beshortened. Thus, in addition to the additional supply of the lightsource, another technical means for increasing the light intensity ofLCD is required. To this end, the development of a light-diffusing film,which functions to allow light emitted from a light source lamp to passthrough a diffusion plate or a light guide plate while being uniformlydiffused without loss, has been proposed as a solution appropriate forincreasing the light efficiency of a backlight unit. Therefore, thoroughresearch into methods of conferring high total light transmittance andhaze to the light-diffusing film is being conducted.

In this regard, Japanese Patent Laid-open Publication No. Hei. 09-270104discloses a technique for preparing a light-diffusing resin laminatehaving a resin layer prepared by uniformly dispersing a light-diffusingmaterial in a base resin containing rubber polymer. Japanese PatentLaid-open Publication No. Hei. 11-164649 discloses a light-diffusingfilm comprising a transparent substrate having a fine roughness on onesurface thereof and a light-diffusing layer formed of an ionizingradiation curable resin on the other surface of the transparentsubstrate. However, such conventional techniques are disadvantageousbecause limitations are imposed on increasing the light transmittanceand light diffusibility of the light-diffusing film, merely by using thelight-diffusing material or partially changing the light-diffusingsurface.

SUMMARY

Leading to the present invention, intensive and thorough research intolight-diffusing films, carried out by the present inventors aiming toavoid the problems encountered in the related art, resulted in thefinding that pores can be formed in a light-diffusing layer laminated onone surface of a base sheet of a light-diffusing film, whereby the lighttransmittance and light diffusibility of the light-diffusing film can beincreased.

Accordingly, an object of the present invention is to provide alight-diffusing film having pores, which has improved total lighttransmittance and light diffusibility.

Another object of the present invention is to provide a light-diffusingfilm, comprising a base sheet, a light-diffusing layer having poreslaminated on one surface of the base film, and an antiblocking layerlaminated on the other surface of the base film.

In order to accomplish the above objects, the present invention providesa light-diffusing film having pores, comprising a base sheet composed ofa synthetic resin; a light-diffusing layer having pores laminated on onesurface of the base sheet; and an antiblocking layer laminated on theother surface of the base sheet; in which said pores are formed byapplying a composition including a light-diffusing resin andlight-diffusing particles contained in the light-diffusing resin undercomposition supply pressure of 1˜5 kgf/cm² and travel speed of the basesheet of 10˜200 m/min.

The light-diffusing layer may be 0.2˜500 μm thick, and the antiblockinglayer may be 0.1˜100 μm thick.

The composition may comprise 100 parts by weight of the light-diffusingresin and 0.1˜1000 parts by weight of the light-diffusing particles,including any one selected from the group consisting of acrylic resin,polyurethane, polyvinyl chloride, polystyrene, polyacrylonitrile,polyamide, and polymethylmethacrylate.

The composition may further comprise 0.01˜10 parts by weight of afoaming agent. As such, the foaming agent may comprise any one inorganicfoaming agent selected from the group consisting of carbonium carbonate,ammonium azoate, sodium borohydride, and azides; any one organic foamingagent selected from the group consisting of chlorofluorocarbons, azocompounds, hydrazide compounds, and nitroso compounds; or mixturesthereof.

Additional features and advantages are described herein, and will beapparent from, the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view schematically showing a light-diffusingfilm, according to the present invention.

DETAILED DESCRIPTION

Hereinafter, a detailed description will be given of the presentinvention.

A light-diffusing film 1 having pores 7 of the present inventioncomprises a base sheet 2 composed of a synthetic resin; alight-diffusing layer 3 laminated on one surface of the base sheet 2;and an antiblocking layer 4 laminated on the other surface of the basesheet 2. As such, when a composition including a light-diffusing resin 6and light-diffusing particles 5 contained in the light-diffusing resin 6is applied on one surface the base sheet, the supply pressure of thecomposition and the travel speed of the base sheet are controlled to 1˜5kgf/cm² and 10˜200 m/min, respectively, thus forming pores 7.

As the base sheet 2 of the present invention, any one selected from thegroup consisting of polyethyleneterephthalate, polyethylenenaphthalate,acrylic resin, polycarbonate, polystyrene, polyolefin, and celluloseacetate is preferably used, but the present invention is not limitedthereto. Since the base sheet 2 functions to transmit light emitted froma light source, it is preferably composed of a synthetic resin having ashigh a light transmittance as possible. The base sheet 2 is preferablyformed to a thickness of 10˜500 μm, and more preferably 75˜250 μm. Ifthe base sheet 2 is thinner than 10 μm, a curling phenomenon may becaused by the resin composition constituting the light-diffusing layer3. On the other hand, if the base sheet 2 is thicker than 500 μm, theluminance of the LCD is decreased and a problem in that manufacturing aslim LCD is impossible may occur.

The pores 7 of the light-diffusing layer 3 are preferably formed byapplying the light-diffusing layer composition including thelight-diffusing resin and the light-diffusing particles contained in thelight-diffusing resin at controlled supply pressure of the compositionand travel speed of the base sheet. In such a case, the supply pressureis 1˜5 kgf/cm², and preferably 2˜4 kgf/cm², and the travel speed is10˜200 m/min, and preferably 15˜100 m/min. If the supply pressure isless than 1 kgf/cm² or the travel speed is less than 10 m/min, the poresare insufficiently formed in the light-diffusing layer. On the otherhand, if the supply pressure exceeds 5 kgf/cm² or the travel speedexceeds 200 m/min, the resin composition constituting thelight-diffusing layer 3 is difficult to apply.

In addition, the light-diffusing layer composition for use in theformation of the pores 7 may further include an inorganic foaming agent,an organic foaming agent, or mixtures thereof. As such, the inorganicfoaming agent preferably comprises at least one selected from the groupconsisting of carbonium carbonate, ammonium azoate, sodium borohydride,and azides, and the organic foaming agent preferably comprises at leastone selected from the group consisting of chlorofluorocarbons, includingtrichlorofluoromethane, dichlorofluoromethane, etc.; azo compounds,including azobisisobutyronitrile, azodicarbonamide, etc.; hydrazidecompounds, including toluene sulfonylhydrazide,4,4′-oxybis(benzenesulfonylhydrazide), arylbis(sulfonylhydrazide), etc.;and nitroso compounds, including N,N′-dinitrosopentamethylenetetramine,etc. The foaming agent is preferably used in an amount of 0.01˜10 partsby weight, and more preferably 0.1˜1 parts by weight, based on 100 partsby weight of the light-diffusing layer composition. If the amount offoaming agent is less than 0.01 parts by weight, the pores areinsufficiently formed in the light-diffusing layer. On the other hand,if the amount exceeds 10 parts by weight, excess pores are generated andthus formation of pores having a desired shape is interrupted.

In the present invention, the light-diffusing layer 3 has pores formedby applying the composition including the light-diffusing resin 6 andthe light-diffusing particles 5 contained in the light-diffusing resin6. The light-diffusing resin 6 preferably comprises a curable resin, andmore preferably a thermosetting resin, in consideration of handlingproperties and availability. Examples of the thermosetting resininclude, but are not limited to, any one selected from the groupconsisting of urea resin, melamine resin, phenol resin, epoxy resin,unsaturated polyester resin, alkyd resin, urethane resin, acrylic resin,polyurethane, fluorine resin, silicon resin, and polyamideimide (PAI).Moreover, the light-diffusing resin should be preferably colorless andtransparent, since light must be transmitted therethrough. Thelight-diffusing resin may further include a plasticizer, a stabilizer, adeterioration preventing agent, a dispersant, an antifoaming agent, or afoaming agent, in addition to the above-mentioned resin.

The light-diffusing particles 5 comprise at least one material selectedfrom the group consisting of acrylic resin, polyurethane, polyvinylchloride, polystyrene, polyacrylonitrile, polyamide, andpolymethylmethacrylate, and are preferably in spherical form. Moreover,it is preferred that the light-diffusing particles be colorless andtransparent so as to maximize the amount of light passing through thelight-diffusing film. The light-diffusing particles have a diameter of0.1˜100 μm, and preferably 1˜50 μm. If the diameter is less than 0.1 μm,the light-diffusing effect becomes insufficient. On the other hand, ifthe diameter exceeds 100 μm, the resin composition constituting thelight-diffusing layer is difficult to apply and the particles may becomedetached from the laminated light-diffusing layer.

As such, the ratio of light-diffusing resin 6 and light-diffusingparticles 5 is adjusted, and thus the optical properties of thelight-diffusing film of the present invention may be controlled. Inparticular, in order to manufacture a light-diffusing film having totallight transmittance of 85˜95%, the light-diffusing layer 3 is formedsuch that the light-diffusing particles 5 are used in an amount of0.1˜1000 parts by weight, and preferably 10˜500 parts by weight, basedon 100 parts by weight of the light-diffusing resin 6. If the amount oflight-diffusing particles 5 is less than 0.1 parts by weight, thelight-diffusing effect is reduced. On the other hand, if the amountexceeds 1000 parts by weight, the resin composition constituting thelight-diffusing layer 3 is difficult to apply.

In addition, the thickness of the light-diffusing layer 3 is adjusted,thereby controlling the light transmittance. Particularly, with theintention of manufacturing a light-diffusing film having total lighttransmittance of 85˜95%, the light-diffusing layer 3 is applied to athickness of 0.2˜500 μm, and preferably 2˜200 μm. If the light-diffusinglayer is applied to a thickness less than 0.2 μm, it has low adhesion tothe film upon application, and the light-diffusing particles may becomedetached from the laminated light-diffusing layer. On the other hand, ifthe applied layer is thicker than 500 μm, total light transmittance isnot higher than 84%, and thus a desired light-diffusing film cannot bemanufactured.

In the present invention, the antiblocking resin 8 used in theantiblocking layer 4 preferably includes a curable resin, and morepreferably a thermosetting resin, in consideration of handlingproperties and availability. Examples of the thermosetting resininclude, but are not limited to, urea resin, melamine resin, phenolresin, epoxy resin, unsaturated polyester resin, alkyd resin, urethaneresin, acrylic resin, polyurethane, fluorine resin, silicon resin, andpolyamideimide. The antiblocking resin should be colorless andtransparent since light must be transmitted therethrough. In addition,the antiblocking resin may further include a plasticizer, a stabilizer,a deterioration preventing agent, a dispersant, an antifoaming agent, afoaming agent or a waxing agent.

The antiblocking particles 9 used in the antiblocking layer 4 includeany one selected from the group consisting of acrylic resin,polyurethane, polyvinyl chloride, polystyrene, polyacrylonitrile,polyamide, and polymethylmethacrylate, and are preferably in sphericalform. As well, the antiblocking particles should be preferably colorlessand transparent in order to enhance the amount of light passing throughthe light-diffusing film. The antiblocking particles have a diameter of0.1˜100 μm, and preferably 1˜50 μm. If the diameter of antiblockingparticles is less than 0.1 μm, a blocking phenomenon, which impedes thetravel of the film, may occur during the process. On the other hand, ifthe diameter of antiblocking particles exceeds 100 μm, the resincomposition constituting the antiblocking layer is difficult to apply,and furthermore, the antiblocking particles may become detached from thelaminated antiblocking layer. Moreover, the antiblocking layer 4 isformed such that the antiblocking particles 9 are used in an amount of0.01˜500 parts by weight, and preferably 0.1˜100 parts by weight, basedon 100 parts by weight of the antiblocking resin 8. If the amount ofantiblocking particles is less than 0.01 parts by weight, a blockingphenomenon, which impedes the travel of the film, may occur during theprocess. On the other hand, if the above amount exceeds 500 parts byweight, it is difficult to apply the resin composition constituting theantiblocking layer 4.

In order to assure high light transmittance and antiblocking function,the thickness of the antiblocking layer 4 may be controlled.Particularly, with the aim of obtaining total light transmittance of85˜95%, the antiblocking layer 4 is applied to a thickness of 0.1˜100μm, and preferably 1˜50 μm. If the antiblocking layer is applied to athickness less than 0.1 μm, it has low adhesion to the base sheet uponapplication and also the antiblocking particles may become detached fromthe laminated antiblocking layer. On the other hand, if the antiblockinglayer is thicker than 100 μm, total light transmittance is decreased,and thus it is impossible to manufacture a desired light-diffusing film.

In addition, of the process of assembling BLU using a light-diffusingfilm, an antistatic agent may be added to or applied on the antiblockinglayer of the light-diffusing film to prevent the introduction ofimpurities due to static electricity. As such, the antistatic agent maybe exemplified by a cationic antistatic agent, an anionic antistaticagent, an amphoteric antistatic agent, a nonionic antistatic agent, apolymer-type antistatic agent, etc. Preferably, the cationic antistaticagent having excellent antistatic properties is used. The cationicantistatic agent is selected from the group consisting of quarternaryammonium salts, pyridinium salts, and mono-, sec-, and tert-aminogroups. In addition, the anionic antistatic agent is selected from thegroup consisting of sulfonates, sulfate esters, phosphate esters, andphosphonates. In the present invention, the antistatic agent should beappropriately selected, in consideration of antistatic properties andheat resistance.

A better understanding of the present invention may be obtained in lightof the following examples, which are set forth to illustrate, but arenot to be construed to limit the present invention.

EXAMPLE 1

On one surface of a highly transparent polyester film (XG533-100 μm,available from Toray Saehan Inc.), a light-diffusing layer compositioncomprising components according to the component ratio shown in Table 1below was applied using a die coater under process conditions shown inTable 1, and then dried at 110° C. for 60 sec, thus forming alight-diffusing film having a 30 μm thick light-diffusing layer. TABLE 1Light-Diffusing Layer Composition and Process Conditions Total Weight ofComposition 100 g  Light- Light-Diffusing Acrylic Resin (A-811, 30 gDiffusing Resin Aekyung Chemical Co. Ltd.) Layer Light-Diffusing SOKENMX1000 30 g Composition Particles (Diameter: 10 μm) SolventMethylethylketone 40 g Process Supply Pressure 3 kgf/cm² Conditions ofComposition Travel Speed of 40 m/min Base Sheet

On the other surface of the light-diffusing film, an antiblocking layercomposition comprising components according to the component ratio shownin Table 2 below was applied using a Mayer bar and then dried at 110° C.for 40 sec, thus forming a light-diffusing film having a 5 μm thickantiblocking layer. TABLE 2 Antiblocking Layer Composition Total Weightof Composition 100 g Antiblocking Antiblocking Acrylic Resin (A-811, 28g Layer Resin Aekyung Chemical Co. Ltd.) Composition Antiblocking SOKENMX300 0.5 g Particles (Diameter: 3 μm) Solvent Methylethylketone 70 gAntistatic Anionic Antistatic Agent 1.5 g Agent (CHEMISTAT3111)

EXAMPLE 2

A light-diffusing layer composition comprising components according tothe component ratio shown in Table 3 below was applied on one surface ofa highly transparent polyester film (XG533-100 um, available from ToraySaehan Inc.) using a Mayer bar and then dried at 110° C. for 60 sec,thus forming a light-diffusing film having a 30 μm thick light-diffusinglayer. TABLE 3 Light-Diffusing Layer Composition Total Weight ofComposition 100 g Light-Diffusing Light-Diffusing Acrylic Resin 30 gLayer Resin (A-811, Aekyung Composition Chemical Co. Ltd.)Light-Diffusing SOKEN MX1000 30 g Particles (Diameter: 10 μm) SolventMethylethylketone 40 g Foaming Agent Microsphere 50D, 0.1 g (0.1 wt partbased on total weight of composition) Process Supply Pressure of 3kgf/cm² Conditions Composition Travel Speed of 40 m/min Base Sheet

An antiblocking layer composition comprising components according to thecomponent ratio shown in Table 4 below was applied on the other surfaceof the light-diffusing film using a Mayer bar and then dried at 110° C.for 40 sec, thus forming a light-diffusing film having a 5 μm thickantiblocking layer. TABLE 4 Antiblocking Layer Composition Total Weightof Composition 100 g Antiblocking Antiblocking Resin Acrylic Resin 28 gLayer (A-811, Aekyung Composition Chemical Co. Ltd.) Antiblocking SOKENMX300 0.5 g Particles (Diameter: 3 μm) Solvent Methylethylketone 70 gAntistatic Agent Anionic Antistatic Agent 1.5 g (CHEMISTAT3111)

COMPARATIVE EXAMPLE 1

A light-diffusing layer composition comprising components according tothe component ratio shown in Table 5 below was applied on one surface ofa highly transparent polyester film (XG533-100 μm, available from ToraySaehan Inc.) using a Mayer bar and then dried at 110° C. for 60 sec,thus forming a light-diffusing film having a 30 μm thick light-diffusinglayer. TABLE 5 Light-Diffusing Layer Composition Total Weight ofComposition 100 g  Light- Light-Diffusing Acrylic Resin (A-811, Aekyung30 g Diffusing Resin Chemical Co. Ltd.) Layer Light-Diffusing SOKENMX1000 30 g Composition Particles (Diameter: 10 μm) SolventMethylethylketone 40 g

On the other surface of the light-diffusing film, an antiblocking layercomposition comprising components according to the component ratio shownin Table 6 below was applied using a Mayer bar and then dried at 110° C.for 40 sec, thus forming a light-diffusing film having a 5 μm thickantiblocking layer. TABLE 6 Antiblocking Layer Composition Total Weightof Composition 100 g Antiblocking Antiblocking Resin Acrylic Resin 28 gLayer (A-811, Aekyung Composition Chemical Co. Ltd.) Antiblocking SOKENMX300 0.5 g Particles (Diameter: 3 μm) Solvent Methylethylketone 70 gAntistatic Agent Anionic Antistatic Agent 1.5 g (CHEMISTAT3111)

EXPERIMENTAL EXAMPLE

1. Measurement of Total Light Transmittance and Haze

The light transmittance and light diffusibility of the light-diffusingfilms manufactured in Examples 1˜2 and Comparative Example 1 weredetermined according to the following procedures. While light of 550 nmwas transmitted perpendicular to a 10 cm×10 cm sized light-diffusingfilm sample which had been stood upright, the amount of light wasmeasured using an automatic digital hazemeter available from NipponDenshoku Industries Co., Ltd. The haze was calculated using Equation 1below: $\begin{matrix}{{{Haze}\quad(\%)} = {( \frac{\begin{matrix}{{{totally}\quad{transmitted}\quad{amount}\quad{of}\quad{light}} -} \\{{amount}\quad{of}\quad{straight}\quad{light}}\end{matrix}}{{totally}\quad{transmitted}\quad{amount}\quad{of}\quad{light}} ) \times 100}} & {{Equation}\quad 1}\end{matrix}$

In addition, total light transmittance was calculated using Equation 2below: $\begin{matrix}{{{Total}\quad{Light}\quad{Transmittance}\quad(\%)} = {( \frac{{totally}\quad{transmitted}\quad{amount}\quad{of}\quad{light}}{{amount}\quad{of}\quad{incident}\quad{light}} ) \times 100}} & {{Equation}\quad 2}\end{matrix}$

2. Measurement of Porosity

The porosity of each of the light-diffusing films of Examples 1˜2 andComparative Example 1 was measured using a pore measuring device via amercury penetration process of Micro Metrics.

The results are given in Table 7 below. TABLE 7 Properties ofLight-Diffusing Films of Examples 1˜2 and Comparative Example 1 TotalLight Transmittance (%) Haze (%) Porosity (%) Ex. 1 91 87 0.9 Ex. 2 9389 1.3 C. Ex. 1 86 83 0

As is apparent from Table 7, the light-diffusing films having pores ofExamples 1 and 2 had total light transmittance and light diffusibilitysuperior to the light-diffusing film having no pores of ComparativeExample 1. In addition, in the light-diffusing film of Example 2 havinghigher porosity than the light-diffusing film of Example 1, the lighttransmittance and light diffusibility were further increased. From this,light efficiency could be confirmed to increase in proportion to anincrease in porosity.

As mentioned above, the present invention provides a light-diffusingfilm having pores, which is excellent with respect both to total lighttransmittance and to light diffusibility. Therefore, in the case wherethe light-diffusing film of the present invention is applied to abacklight unit of a TFT-LCD, it can provide high visibility throughoutthe entire surface of the display.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

1. A light-diffusing film having pores, comprising: a base sheetcomprising a synthetic resin; a light-diffusing layer having poreslaminated on one surface of the base sheet; and an antiblocking layerlaminated on a second surface of the base sheet; wherein said pores areformed by applying a composition including a light-diffusing resin andlight-diffusing particles contained in the light-diffusing resin undercomposition a supply pressure of 1 to 5 kgf/cm² and a travel speed ofthe base sheet of 10 to 200 m/min.
 2. The light-diffusing film as setforth in claim 1, wherein the light-diffusing layer is 0.2 to 500 μmthick.
 3. The light-diffusing film as set forth in claim 1, wherein theantiblocking layer is 0.1 to 100 μm thick.
 4. The light-diffusing filmas set forth in claim 1, wherein the composition comprises 100 parts byweight of the light-diffusing resin and 0.1 to 1000 parts by weight ofthe light-diffusing particles.
 5. The light-diffusing film as set forthin claim 1, wherein the composition further comprises 0.01 to 10 partsby weight of a foaming agent.
 6. The light-diffusing film as set forthin claim 5, wherein the foaming agent comprises any inorganic foamingagent selected from the group consisting of carbonium carbonate,ammonium azoate, sodium borohydride, azides; and mixtures thereof. 7.The light-diffusing film as set forth in claim 5, wherein the foamingagent comprises any one organic foaming agent selected from the groupconsisting of chlorofluorocarbons, azo compounds, hydrazide compounds,and nitroso compounds; and mixtures thereof.
 8. The light-diffusing filmas set forth in claim 1, wherein the composition comprises anycomposition selected from the group consisting of acrylic resin,polyurethane, polyvinyl chloride, polystyrene, polyacrylonitrile,polyamide, and polymethylmethacrylate.